Headstock Run-out?

Yes there are set screw marks on the spindle nose. Does the spindle nose taper, wedge the chuck into place? or does it ride on the OD of the spindle nose? The reason I ask is I’m sure the backing plate on the chuck does not wedge itself in the spindle nose. To me it seems to be a close guide, but everything rides on the D6 locks. I went to the website for buck chuck and read the set up instructions, per the instruction If you have more then .0005 run out on the chucks backing plate then you should take a light facing cut on it. I had .0025, so I took a clean up cut adjusted a few of the cam locks, cleaned everything up, and was finally able to dial a part to .0001 however, I’m sure when you cut the part you cutting must be deflected to some degree. I’m still going to check on the price for a new spindle!!

Thanks for everyone’s help you might get sick of all my questions but the help is greatly appreciated.
 
huntinco,

Just a general comment about machine tools - part of using the machine is constantly checking things and truing them up. You seem to be working well at that. The "small" variances you are seeing can be caused by burrs, dents, thread slop, bent parts, improper manufacture, etc. To make sure your setups work, you need to go through the whole machine and true everything (periodically). It will give you peace of mind. The old machinists on this site know this in their bones, because they are used to finding and fixing this sort of problem, but also because work and tool distortions occur frequently.

I once made a tapered 5-C collet adapter to fit the headstock taper of a new (Asian) lathe and couldn' get the runout to be less than about .003". I bought a commercial collet setup and found that the runout was also about the same. The ultimate fix was to re-bore the lathes original headstock center taper, which I did with a carbide boring tool followed by a tool post grinder. This corrected the spindle runout and all issues with the headstock, but you normally would hope that a new machine wouldn't have this sort of problem.

The difference in knowlege/skill level between working steel to .001" and to .0001" or better is vast. I doubt you need a new spindle, but correcting your current misalignments is possible and should probably make your machine OK for gun work. Just keep working at improving your results.

Scott
 
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